Polyphosphoinositide synthesis and platelet shape change.

J H Hartwig; K Barkalow

doi:10.1097/00062752-199704050-00009

Home/Archive/PubMed

PubMed · 9288469

Polyphosphoinositide synthesis and platelet shape change.

J H Hartwig·K Barkalow

View original source ↗Export metadata ↓

Abstract

Polyphosphoinositides both integrate signaling pathways at the cytoplasmic surface of the plasma membrane and serve as the final messenger of signaling pathways. They have a well-defined role in the release of calcium through the degradative pathway. Recent work, however, has highlighted the role of the polyphosphoinositide synthetic pathways in activated cells. This review emphasizes the role of polyphosphoinositides in recruiting signaling proteins that have pleckstrin homology domains and in directly regulating actin assembly in the human blood platelet.

Explore related subjects

1-Phosphatidylinositol 4-Kinase Actins Animals Binding Sites Blood Platelets Blood Proteins GTP-Binding Proteins Humans Models, Biological Phosphatidylinositol Phosphates Phosphoproteins Phosphotransferases (Alcohol Group Acceptor)Platelet Glycoprotein GPIIb-IIIa Complex Protein Conformation Protein Kinase C Signal Transduction Journal Article Review

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

J H Hartwig, K Barkalow. 1997. Polyphosphoinositide synthesis and platelet shape change.. https://doi.org/10.1097/00062752-199704050-00009

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

The role of the phosphoinositides at the Golgi complex.

Eukaryotic cells are organized into a complex system of subcompartments, each with its distinct protein and lipid composition. A continuous flux of membranes crosses these compartments, and in some cases direct connections exist between the different organelles. It is thus surprising that they can maintain their individual identities. Small GTPases and the phosphoinositides have emerged as the key regulators in the maintenance of the identity of the Golgi complex. This property is due to their ability to act either alone or, more often, in combination, as cues directing and controlling the recruitment of proteins that possess phosphoinositide-binding domains. Among these many proteins there are the lipid transfer proteins, which can transfer ceramide, oxysterol, cholesterol and possibly glucosylceramide. By regulating these lipid transfer proteins in this way, this binomial combination of the small GTPases and the phosphoinositides acquires a further important role: control of the synthesis and/or distribution of other important integral constituents of cell organelles, such as the sphingolipids and cholesterol. This role is particularly relevant at the level of the Golgi complex, a key organelle in the biosynthesis, transport and sorting of both lipids and proteins that is located at the intersection of the secretory and endocytic pathways.

1-Phosphatidylinositol 4-Kinase↗

PubMed2006

Nucleolar localization of phosphatidylinositol 4-kinase PI4K230 in various mammalian cells.

BACKGROUND: Previous immunohistochemical investigations could not detect PI4K230, an isoform of mammalian phosphatidylinositol 4-kinases (also called type III alpha), in the nucleus and nucleolus of cells in spite of its predicted nuclear localization signals. METHODS: Immunofluorescent detection of PI4K230 and other PI4K isoforms was performed on formaldehyde (PFA) or ethanol fixed cells and rat brain cryosections. Costaining with nucleolin and the effect of siRNA, Triton X-100, DNase, and RNase treatments were also tested to determine the localization of PI4K230. RESULTS: PI4K230 gives a prominent signal in the nucleolus of ethanol fixed rat brain cryosections and of several cell types in addition to its presence in the nucleus and cytoplasm. The PI4K230 immunoreactivity of the nucleolus is masked in PFA fixed cells, but it can be restored by treatment of PFA fixed cells with hot wet citrate buffer or by washing the cryosections with PBS prior to PFA fixation. Nucleolar PI4K230 occurs in a Triton X-100 resistant complex. Treatment of COS-7 cells with siRNA targeting PI4K230 and permeabilized B50 cells with DNase or RNase results in the loss of PI4K230 signal from the nucleolus. CONCLUSION: These experiments suggest the participation of PI4K230 in a DNase and RNase sensitive complex with a unique localization and function in the nucleolus.

1-Phosphatidylinositol 4-Kinase↗

PubMed2006

Phosphoinositide synthesis and degradation in isolated rat liver peroxisomes.

Analyzing peroxisomal phosphoinositide (PId(#)) synthesis in highly purified rat liver peroxisomes we found synthesis of phosphatidylinositol 4-phosphate (PtdIns4P), PtdIns(4,5)P(2) and PtdIns(3,5)P(2). PtdIns3P was hardly detected in vitro, however, was observed in vivo after [(32)P]-phosphate labeling of primary rat hepatocytes. In comparison with other subcellular organelles peroxisomes revealed a unique PId pattern suggesting peroxisomal specificity of the observed synthesis. Use of phosphatase inhibitors enhanced the amount of PtdIns4P. The results obtained provide evidence that isolated rat liver peroxisomes synthesize PIds and suggest the association of PId 4-kinase and PId 5-kinase and PId 4-phosphatase activities with the peroxisomal membrane.

1-Phosphatidylinositol 4-Kinase↗